1. Field of the Invention
The present invention relates to a fluid machine such as a scroll compressor, in particular, to a scroll compressor applied to a refrigerant compressor for a refrigeration apparatus or an air conditioning apparatus.
This application is based on Japanese Patent Application Nos. 2006-164677, 2006-167903, and 2006-173897, the content of which is incorporated herein by reference.
2. Description of Related Art
Conventionally, a fluid machine such as a scroll compressor that compresses gaseous fluid is commonly known.
As an example of this kind of fluid machine, there is a fluid machine that is provided with a funnel-shaped lower pressure side housing having a suction port for introducing low pressure gaseous fluid, and a high pressure side housing having a discharge opening for discharging high pressure gaseous fluid, both housings being integrally connected to form a sealed housing in which a compression mechanism such as a scroll compression mechanism is accommodated. In this case, the funnel shaped low pressure housing is constructed so that a main body portion of the compression mechanism is arranged on a large diameter wide opening section side, which is connected to the high pressure housing, and a compression mechanism driving section such as a rotation shaft is arranged in a narrow section of small diameter (for example, refer to the Publication of Japanese Patent No. 3227075 (FIG. 1)).
However, in the conventional fluid machine described above, in order to secure the sectional area of a passage for gaseous fluid to be introduced from a suction port provided in the low pressure side casing into the interior of the compression mechanism to be compressed, the dimension of a gap section δ formed between an inner circumferential surface of the low pressure side casing and an outer circumferential surface of the compression mechanism needs to be set greater. Since the diameter of the housing side is increased to secure the required dimensions for this gap section δ, the outer dimensions of the fluid machine increase by this amount, becoming an obstacle to reducing the size of the fluid machine.
Moreover, for example a body section of the low pressure side casing is generally manufactured by aluminum die casting. However, in this case, a corner section from a sidewall surface to a bottom surface for securing strength may have a curved surface of R0 radius. Therefore, as the gap section δ described above, a gap section of at least δ0 (refer to FIG. 3B) for preventing interference between a body section 5A and an orbiting scroll member 27 needs to be set starting at a position on the flat surface at which the curved surface finishes and a thrust receiving surface 5B begins. That is to say, in order to avoid the orbiting scroll member interfering with and riding up the curved surface of the corner section, the gap section 5 from the inner circumferential surface of the body section 5A to a sliding range of the orbiting scroll member 27 needs to be greater than δ0. This also results in an inevitable increase in the outer dimensions of the fluid machine. Since a small draft angle is provided in the aluminum die casting body section 5A for the sake of production convenience, the outline shape becomes larger as it approaches the upper part of the sidewall surface. As a result, the outline shape of the conventional fluid machine is unnecessarily large.
In consideration of this background, a fluid machine structure that enables a reduction in outer dimensions and shape while securing sufficient sectional area of the passage for introducing gaseous fluid introduced from the suction port into the compression mechanism is desired.
Moreover, the scroll compressor is such that a stationary scroll and an orbiting scroll are arranged so as to intermesh with each other inside the housing. A plurality of compression chambers are formed between the stationary scroll and the orbiting scroll. The scroll compressor is constructed such that the orbiting scroll is orbitally driven and the compression chamber is shifted from its outer circumferential position to the center position while its capacity reduces to compress a fluid.
In order to orbitally drive the orbiting scroll with respect to the stationary scroll, a crankshaft is provided in the housing allowing it to freely rotate around its axis. A large diameter shaft section is provided on one end section of this crankshaft. Furthermore, an eccentric pin that is connected to the orbiting scroll via a drive bush and that orbitally drives the orbiting scroll at a predetermined rotation radius, is provided in the large diameter shaft section. The large diameter section of the crankshaft is supported by the housing. The large diameter shaft section is supported in the housing via a main bearing constructed for example from a ball bearing disclosed in the Publication of Japanese No. 2868998. Thus, the crankshaft is supported, allowing it to freely rotate around its axis.
A seal member that seals off (separates) the interior of the housing from the outside, is provided on the other end side of the crankshaft.
For example, in a scroll compressor used in a refrigeration cycle, the refrigerant sucked in is introduced between an inner ring and an outer ring of the bearing, and lubrication oil contained in the refrigerant lubricates the bearing.
In the case of the ball bearing, the components thereof are in point-contact with each other (inner ring and ball, ball and outer ring). Therefore, the ball bearing becomes a comparatively large structure corresponding to the load to be supported, and a gap for carrying out sufficient refrigerant introduction into the interior can be secured. On the other hand, if a ball bearing is used for the main bearing, there will be a problem of an increase in the size of the housing.
In this kind of scroll compressor, a greatest reduction in size and weight possible is required for the sake of installation. Therefore, a main bearing that uses a needle shaped roller bearing having an outer ring to reduce the size of the housing, as disclosed for example in Japanese Unexamined Patent Application, Publication No. 2000-2250, has been proposed.
However, the gap within the interior of the needle shaped roller bearing having an outer ring is small compared to a ball bearing. As a result, if the needle shaped roller bearing having an outer ring is used as a main bearing, insufficient refrigerant is introduced into the bearing, raising the possibility of insufficient lubrication for the bearing.
For this reason, in a needle shaped roller bearing having an outer ring, disclosed in Japanese Unexamined Patent Application Publication No. 2000-2250 the shape of an end section in the axial direction of the outer ring is devised so as to secure a gap for introducing refrigerant.
However, since the roller bearing disclosed in Japanese Unexamined Patent Application, Publication No. 2000-2250 needs to use a needle shaped roller bearing having an outer ring in a special shape, there is a problem of an increase in production cost.
Furthermore, a scroll compressor is disclosed in Japanese Unexamined Patent Applications, Publication Nos. 2000-108647 and 2000-320477 in which a scroll compressor houses a scroll compression mechanism constructed from a pair of a stationary scroll member and an orbiting scroll member within a housing constructed from a funnel shaped front housing and a rear housing connected to a large diameter opening section of the front housing, the stationary scroll member being fixed and installed in the rear housing, a seal member being placed between an end plate of the stationary scroll member and the housing, the interior of the housing being separated into a high pressure discharge chamber side and a low pressure intake chamber side.
Here, the stationary scroll member is constructed from an end plate and a spiral wrap standing upright on one side of this end plate so that its axis is substantially orthogonal thereto. In the same way, the orbiting scroll member is constructed from an end plate and a spiral wrap standing upright on one side of this end plate so that its axis is substantially orthogonal thereto.
Moreover, a scroll compressor proposed in Japanese Examined Patent Application, Publication No. Sho 60-17956, that houses a scroll compression mechanism constructed from a pair of a stationary scroll member and an orbiting scroll member within a housing constructed from a cup shaped rear housing and a front housing connected to a large diameter opening section of this rear housing, employs the following construction. Specifically, in Japanese Examined Patent Application, Publication No. Sho 60-17956, there is proposed a scroll compression mechanism capable of performing three dimensional compression that enables compression in the circumferential direction and in the wrap height direction, in which step sections are respectively provided on a tip end surface (the end surface facing the side opposite to the end plate) and a bottom surface (area exposed to the space within the spiral wrap on the end plate) of the respective spiral wraps of the stationary scroll member and the orbiting scroll member, and the wrap height on the outer circumference side of the spiral wrap (length from the bottom surface to the tip end surface of the spiral wrap) is higher than the wrap height on the inner circumference side. Furthermore, in Japanese Examined Patent Application, Publication No. Sho 60-17956, there is proposed a construction in which the stationary scroll member of the scroll compression mechanism is fixed and installed on the rear housing side with a seal member placed between the end plate of the stationary scroll member and the housing, and the interior of the housing is separated to form a high pressure discharge chamber side and a low pressure intake chamber side.
However, in the scroll compressor disclosed in Japanese Unexamined Patent Applications, Publication Nos. 2000-108647 and 2000-320477 mentioned above, a seal member that seals off the interior of the housing from the atmospheric air is arranged between the high pressure discharge chamber and the atmospheric air. As a result, there is a problem in that high pressure gas may leak directly into the atmospheric air in the case where a failure occurs in the seal member or leakage occurs due to an unusual rise in high pressure.
Moreover, the above seal member is arranged in a diameter position substantially equal to that of the inner diameter of the housing or the outer diameter of the end plate of the stationary scroll member. According to such construction, a high pressure load is applied on the entirety of the surfaces of the housing and the stationary scroll member end plate, and the area that receives pressure load due to this high pressure is maximized. As a result, there is a possibility of gas leakage due to minute deformation in the housing and the end plate caused by excessive pressure load. Therefore, it is necessary to increase the rigidity of the housing and the end plate by increasing their plate thickness, resulting in an increase in weight of the compressor that obstructs a reduction in the weight of the compressor.
In addition, a scroll compressor disclosed in Japanese Examined Patent Application, Publication, No. Sho 60-17956 has a construction that does not allow direction leakage of high pressure gas from the discharge chamber into the atmospheric air, due to an arrangement and construction of the housing and seal member mentioned above. However, since the above seal member is arranged on the outer circumference of the end plate of the stationary scroll member, there is no difference whatsoever between the construction of Japanese Unexamined Patent Application, Publication No. 2000-108647 and Japanese Unexamined Patent Application, Publication No. 2000-320477 with respect to the area of portions of the housing and the stationary scroll member end plate that receive pressure load due to high pressure.
Therefore, problems related to gas leakage due to minute pressure deformation, and an increase in the weight of the compressor as a result of increasing the rigidity of the housing and the end plate as a counter measure for the leakage, are yet to be resolved in reality.
In particular, achieving a reduction in weight of a compressor to be applied to an air conditioning apparatus for a vehicle has been one of the most significant problems.